Various automated hemapheresis systems for separating whole blood into two or more of its constituents have been utilized in the past. Such devices are shown in Schoendorfer U.S. Pat. No 4,851,126 and Schoendorfer et al. U.S. Pat. No. 5,188,588, the disclosures of which are incorporated herein by reference.
Such systems are adapted for blood cell separation generally and often specifically for platelet separation. In general, such systems collect whole blood from the donor, separate the desired cells and return the remaining blood components to the donor usually through a single needle. Although a separate return needle can be used, it is preferred that a single venepuncture needle be used both for collection and reinfusion. Hemapheresis systems generally include a disposable set of bags, reservoirs and conduits. The use of peristaltic pumps to cause the blood fluids to move through the system is preferred because the blood and separated blood components can be moved through the device while it is wholly contained within the sterile disposable components, which are commonly referred to as a harness set. Harness sets include, at least, one venepuncture needle, at least one separation device for separating blood into its components, and at least one reservoir for containing blood. A plurality of conduits connects the needle, the separation device and the reservoir to each other. The conduits include a section formed of flexible elastomeric material so that blood can be moved through the conduits by means of peristaltic roller pumps.
The preferred type of system includes, as a minimum, a single venepuncture needle, separation means for separating at least one constituent from whole blood, first and second reservoirs containing blood, a first conduit interconnecting the needle and the first reservoir, a second conduit interconnecting the first reservoir and the separation means, a third conduit interconnecting the separation means and the second reservoir, and a fourth conduit for returning blood components to the needle. Preferably, four separate peristaltic pumps are provided to move the blood and the blood components through the conduits.
Typically, systems of this general type also include a microprocessor for controlling a number of pumps, clamps, detectors, monitoring systems, et cetera, for automating the collection of whole blood from the donor, separating the blood into plasma and cell concentrate, collecting the plasma and reinfusing the cell concentrate into the donor using the harness set applied to the instrument. After application of venepuncture to the blood donor, the instrument operates between alternating collection and reinfusion cycles. In the collection cycle, anticoagulated whole blood is pumped by a blood pump to the separator of the harness where it is separated into plasma which flows into a collection container and cell concentrate which flows to a reinfusion reservoir. In the reinfusion cycle, the blood pump reverses to flow cell concentrate from the reservoir through the phlebotomy needle to the donor.
Peristaltic pumps are also used for the delivery of other liquids such as medications, additives to fluid mixing processes, etc. A need has continued to exist for such apparatus that is compact and easy to use.